1. Field of Invention
The invention relates to broadband communication networks, and in particular to access protocols used in a local area broadband communication networks.
2. Related Art
The worldwide utilization of external television (“TV”) antennas for receiving broadcast TV, cable television (CATV), and satellite TV is growing at a rapid pace. These TV signals received via an external TV antenna, cable TV and satellite TV, such as a direct broadcast satellite (“DBS”) system, are usually located on the exterior of a building (such as a home or an office) and enter the building at a point-of-entry (“POE”). Multiple TV receivers, audio video receivers, and/or video monitor devices may be located within the building and these multiple devices may be in signal communication with the POE via a broadband cable network that may include a plurality of cables and cable splitters. Generally, these cable splitters are passive devices and distribute downstream signals from the POE to various terminals (also known as “nodes”) in the building. The nodes may be various types of customer premise equipment (“CPE”) such as cable converter boxes, televisions, video monitors, cable modems, cable phones, audio video receivers, set-top boxes (STBs) and video game consoles.
Within a typical building or home, there may be a mixture of coaxial cables of varying types and quality, such as RG-59, RG-6, and RG-6 quad shield, thus creating a less than optimal RF environment within the cable. Further, typical homes do little or no termination of cable outlets enabling the introduction of RF interference into the coaxial cables. Another problem often encountered with a typical home or building coaxial cable configuration is the use of multiple splitters of varying quality and frequency ranges. This also creates a problem for known approaches to local area networking over coaxial cable. Such networking often requires a more controlled RF environment or higher quality cabling to support higher frequency ranges.
Typically, an STB connects to a coaxial cable at a wall outlet terminal and receives cable TV and/or satellite TV signals. A device, such as the STB, connected to the coaxial cable may be called a node. Usually, the STB receives the cable TV and/or satellite TV signals and converts them into tuned RF TV signals that may be received by the TV receiver and/or video signals that may be received by a video monitor.
In FIG. 1, an example of a known broadband cable network 100 (also known as a “cable system” and/or “cable wiring”) is shown within a building 102 (also known as customer premises) such as a typical home or office. The broadband cable system 100 may be in signal communication with an optional cable service provider 104, optional broadcast TV station 106, and/or optional DBS satellite 108, via signal path 110, signal path 112 and external antenna 114, and signal path 116 and DBS antenna 118, respectively. The broadband cable system 100 also may be in signal communication with optional CPEs 120, 122 and 124, via signal paths 126, 128 and 130, respectively.
In FIG. 2, another example of a known broadband cable system is shown within a building (not shown) such as a typical home. The cable system 200 may be in signal communication with a cable provider (not shown), satellite TV dish (not shown), and/or external antenna (not shown) via a signal path 202 such as a main coaxial cable from the building to a cable connection switch (not shown) outside of the building. The cable system 200 may include a multi-tap device (not shown) that allows communication to neighboring homes, a POE to the home 204, N:1 Splitter 206, which in this system may also be considered a Root Node, sub-splitter 208, and node devices 210, 212 and 214.
Within the cable system 200, the Multi-Tap (not shown) may be in signal communication with the Root Node/main splitter 206 via signal path 228. The Root Node/main splitter 206 may be the connection point from the cable provider that is located externally to the building of the cable system 200. The Root Node/main splitter 206 may be implemented as a coaxial cable splitter that may include passive devices and packages including connectors, transformer and/or filters.
The N:1 splitter 206 (a 2:1 splitter in FIG. 2) acts as the main splitter and may be in signal communication with N:1 sub-splitter 208 (a 2:1 splitter in FIG. 2), and node device 210, via signal paths 230 and 232, respectively. The N:1 sub-splitter 208 may be in signal communication with node devices 212 and 214 via signal paths 234 and 236, respectively. The node devices may be comprised of numerous known STB coaxial units such as cable television STBs and/or satellite television STBs, as well as various video and multimedia devices typically found in the home or office. Typically, the signal paths 228, 230, 232, 234, and 236 may be implemented utilizing coaxial cables 216, 218, 220, 222 and 224, respectively.
In an example operation, the cable system 200 would receive CATV, cable and/or satellite radio frequency (“RF”) TV signals 226 from the Multi-Tap (not shown) via signal path 216 into the Root Node/main splitter 206. The Root Node/main splitter 206 may pass, transform and/or filter the received RF signals to a second RF signal 230 that may be passed to N:1 sub-splitter 208 via signal path 218. Sub-splitter 208 may then split the second RF signal 230 into split RF signals 234 and 236 that are passed to node devices 212 and 214 via signal paths 222 and 224, respectively. If the node device is an STB, the node device may convert the received split RF signal into a baseband signal (not shown) that may be passed to a video monitor (not shown) in signal communication with the STB. Similarly, the Root Node/Main Splitter passes a second signal 232 via signal path 220 to another node device 210.
In recent years, numerous consumer electronics appliances and software applications have been developed and continue to be developed that are able to receive, store, process and transmit programming information to multiple devices in the home at the time and manner as determined by the viewer. The main drawback to the ability of users to view multimedia information stored on multiple storage devices at the home and view it (or listen to it) on any capable home appliance at the time and manner of his choosing is the lack of a viable home networking solution. There are large numbers and types of CPEs that can be utilized and shared in such a fashion including televisions, video monitors, cable modems, cable phones, video game consoles, and audio components, as well as various storage devices. There is a growing need for different CPEs to communicate between themselves in a network type of environment within the building. As an example, users in a home may want to share other types of digital data (such as video and/or computer information) between different devices in different rooms of a building.
The present invention is focused on utilizing the home coaxial cable as a medium for high speed home networking by utilizing frequencies above the ones currently used by the Cable Operators for their cable service. The home coaxial cable is a natural medium for connecting multimedia devices since it has an enormous amount of available bandwidth required for the high data rates that are needed for such applications and also, all the multimedia devices and appliances are most likely to be already connected to the coaxial cable. Unfortunately, most broadband cable networks (such as the examples shown in both FIG. 1 and FIG. 2) presently utilized within most existing buildings are not configured to allow for networking between CPEs. Most broadband cable networks utilize broadband cable splitters that are designed to split an incoming signal from the POE into numerous split signals that are passed downstream to the different nodes in different rooms, or equivalently, combine signals from multiple sources (on the “output” ports) to an aggregate on the “input” port. The existing conventional wisdom is that the use of splitters in the existing broadband cable networks make these networks able to communicate only between the “point of entry” 204 and node devices 210, 212, and 214, and prevents direct networking between node devices in the network because signals returning from the node devices cannot be routed back through the splitters, i.e., cannot “jump” a splitter. The present invention describes a system that allows node devices (“CPEs”) to communicate directly over the existing coaxial cable with its current architecture without the need to modify the home cable infrastructure.
As an example, in a typical home the signal splitters are commonly coaxial cable splitters that have an input port and multiple output ports. Generally, the input port is known as a common port and the output ports are known as tap ports. These types of splitters are generally passive devices and may be constructed using lumped element circuits with discrete transformers, inductors, capacitors, and resistors and/or using strip-line or microstrip circuits.
Presently many CPEs utilized in modern cable and DBS systems, however, have the ability to transmit as well as receive. If a CPE is capable of transmitting an upstream signal, the transmitted upstream signal from that CPE typically flows through the signal splitters back to the POE and to the cable and/or DBS provider. In this reverse flow direction, the signal splitters function as signal combiners for upstream signals from the CPEs to the POE. Usually, most of the energy from the upstream signals is passed from the CPEs to the POE because the splitters typically have a high level of isolation between the different connected terminals resulting in significant isolation between the various CPEs.
The isolation creates a difficult environment in which to network between the different CPEs because the isolation results in difficulty for transmitting two-way communication data between the different CPEs. However, CPEs are becoming increasingly more capable and a growing number of users desire to network multiple CPEs to share storage and capabilities across the network. As CPEs are networked together in this difficult environment, the problem of coordinating network resources, accesses and optimizing communications between CPEs becomes a necessity.
Therefore, there is a need for a system and method to connect a variety of CPEs into a local data network, such as a local area network (“LAN”), within a building such as a home or office, while utilizing an existing coaxial cable network within the building. Additionally, there is a need for coordinating network resources, access to the network, and to optimize the communication between CPEs.